Phosphoinositide polyphosphates (PtdInsPns), biosynthesized by the interplay of kinases and phosphatases, are key signaling molecules in cellular communication. The lipid kinase, phosphatidylinositol 3-kinase (PI 3-K) has been identified in the control of diverse cellular processes such as proliferation and differentiation, tumorigenesis, and apoptosis. The use of PI 3-K and its lipid products, PtdIns(3,4,5)P2 and PtdIns(4,5)P2, as potential tumor markers in the early detection of cancer would be substantially enhanced with the development of rapid 96-well format assay kits for lipid kinase activity. Vast clinical isolets from epithelial cancer origin could be screened in such a high throughput assay format. Echelon Research Laboratories (ERL) has developed syntheses of commericalized PtdInsPns. In our second tier strategy, these PtdInsPns as well as licensed monoclonal antibodies against phosphoinositides will be employed to prepare assay plates containing a specific immobilized substrate using Flashplate(TM) and ELISA technologies, respectively. We will focus on the use of PtdIns(4,5)P2 as a substrate for PI 3-K to develop and optimize assay kits against benchmark techniques. Subsequent screening of various types of epithelial cancer isolets will be pursued to determine the significance of PI 3-K and its lipid products as a reliable diagnostic tool in cancer research. PROPOSED COMMERCIAL APPLICATIONS: The research would lead to production of 96-well assay kits for rapid testing of PI 3-K as a potential tumor marker in clinical isolets taken from various origins of epithelial cancer cells. Systematic screening of multiple cancerous cell extracts will allow rapid detection of tissue- or physiology- specific activities. Screening of libraries of compounds will allow detection of potential isozyme-specific inhibitors as therapeutic leads. Major pharmaceutical companies, numerous biotech start-ups, and hundreds of academic laboratories would employ such kits for basic and applied research.